"Key is not present in table" - database problem after Django deployment

I'm having a problem when trying to add objects to my database in my app. I just deployed this app and it's working on my local installation, where I'm using sqlite. On my webfaction deployment, I'm using postgre.

I get the following error:

IntegrityError at /app/project/
insert or update on table "app_project" violates foreign key constraint "app_project_owner_id_fkey"
DETAIL:  Key (owner_id)=(1) is not present in table "app_user".
Request Method: POST
Request URL:    http://username.webfactional.com/app/project/
Django Version: 1.2.3
Exception Type: IntegrityError
Exception Value:    
insert or update on table "app_project" violates foreign key constraint "app_project_owner_id_fkey"
DETAIL:  Key (owner_id)=(1) is not present in table "app_user"

It seems that I have not been able to create the database properly. I'm able to add users in my admin and register new users from my django app, but I keep getting this "foreign key constraint" error when trying to add other objects that require users as a foreign key. In the phpPgAdmin, there are no rows in flow_user, so apparently it's not correctly creating the users? I'm using south for migrations which might have created an error?

Is there something I might need to do change in my models to get my django app working in postgre after using sqlite?

Any ideas how to correct this error, recreate the database or why this error has arised?